Telephone-exchange system.



APPLICATION I'ILED JAN. 28, 1905.

Patented May 21, 1912.

npantoz EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented May 21, 1912.

Application filed January 28, 1905. Serial No. 243,114.

To all whom it may concern:

tems, of which the following is a specification, reference being hadtherein to the accompanying drawing.

My invention relates to telephone eX- change systems, and has for itsobject the production of a common battery system, in

which either two-wire or three-wire line circuits may be employed,together with two conductor cord-circuits.

A portion of the invention relates to th line circuits specifically, butthe cord-circuit may be employed to tie together difierent linecircuits, and may be arranged so as to operate successfully inconnection with a number of recognized standard circuits.

In many cases heretofore, the 7 common battery at central has beenconnected in a bridge across each cord circuit, and local circuits forlamp or other signals have been controlled by relays responding to thecurrent flow in the battery bridge. In order to keep theselocal circuitsand the relay circuits from becoming confused, numerous expedientshave'been resorted to, one being to provide joint control by means oftwo or more relays themselves in dilferent'circuits, and another beingto locate the local signals in circuits closed through third conductorsin the respective cords, the continuity whereof might be controlled bythe connective plugs and jacks. In the present case I dispense with thethirdconductor, provide for a feed through the supervisory relays in thecords to the respective lines they connect, and for a return'for thelines to the battery through their respective cut-off relays, thecurrent so passing serving the double purpose of Supplying thesubscribers transmitters and of working the signals while the cut-01fand supervisory relays servefithe.

double purpose of controlling the signals and of choking out voicecurrents from the battery connections.

The local circuits of -my supervisory lamps, I controlas to their normalcontinuity, by forming them in part of the talking strands of thecord-conductor terminating in the respective plug contacts. When a plugis first inserted, its lamp comes -momentarily into circuit with itscorresponding cut-ofi relay, insuring the operation of the latter, butbeing cut off itself while the lines are in use, thus leaving a clea;talking circuit with no bridges of the cor My, invention is illustratedin the accompanying drawings, wherein- Figure 1 is a diagram showing twosubscribers lines, one with a three-wire jack circuit, and the otherwith a two-wire circuit, together with my improved cord-circuits. Fig. 2shows a modified cord-circuit.

Referring to Fig. 1, A and A are subscribers stations, equipped withapparatus usual in common battery exchange systems.

From each station line-wires 1 and 2 lead to central oflice, terminatingin the springs j, y" of the jacksJ and J of the switchboard. Beyond thejacks each line has extensions. From the jacks J the, lines 1 and 2 areextended to the armatures m, m of the cutoff relay L, and on one side tothe line or signal relay L; also by the wires 3 and l .to the batterybus-bars 5 and 6, of main battery B, which is grounded. The line orsignal relay L controls the local circuit 8 of the signal lamp Z throughthe front contacts of relay L and back contacts of cut-ofi relay L. Thecut-off relay L is connected by a wire 7 to the ring j of jack J and bythe wire 4 to bus-bar 6 of battery B. From the jacks J the line-wires 1and 2 are extended to the armatures m", m1", of cut-off relay L"; fromthe contact 0 wire 4 goes to the line or signal relayiL 'and ground;while from contact 0 wire 3 goes to the bus-bar 5 of battery B. i

The line or signal relay L controls the local circuitS of signal lamp Zthrough the front contacts of relay L and back contacts of'cut-off relayL The windings of cutoff relay ,L are connected by the wires 3 and 7 tothe contacts 0 and 0 and through the earth to bus-bar 6. of battery B.The armature ,m of cut-off relay L is connected by the wire 7 O to thearmature m of "C and C are inserted in the wires 11, 12,

and 13, 14, respectively, which separatethe answering plug P from thecalling plug P,

so as to permit of double supervision. From the tip wires 11 and 12,respectively, the windings of the supervisory relays S and S areconnected by the wire 15 to bus-bar 5 of battery B. From the sleevewires 13 and 14, respectively, the supervisory lamps s, s are connectedby contacts in the relays S, S, and by the wire 15 to bus-bar 5 ofbattery B.

In Fig. 2, an arrangement is shown whereby the bridging of one condenserin the cordcircuitby the two supervisory relays, as in Fig. 1, isavoided. The tip 79 of the answering plug P is connected by wire 11 tocondenser G and then by the wire 12 to the sleeve 79 of the calling plugP. The sleeve 7) of the answering plug P is connected by the wire 13 tocondenser C and then by the wire 14 to tip p of the calling plug P.Supervisory relays S, S are connected to the wires 11 and 14:,respectively. Supervisory lamps s, s are controlled by relays S and Sthemselves connected to the wires 12 and 13, respectively, andcontrolled by relays S and S. It will readily be seen that the operationof this circuit will be the same as in Fig. 1, and the bridging of anyone of the condensers in the cord-circuit is avoided.

The operation of my system is as follows: The parts are normally in theposition shown in the drawing. Supposing subscriber A calls central, hecloses the line-circuit 1 and 2 and currentflows from the main battery Bthrough the Winding of line-relay L, which attracts its armature andcloses the circuit 8, which causes the lamp Z to glow. The operatorseeing the signal inserts the answering plug P into the jack J and asksin the regular way for the number wanted. Upon the insertion of the plugP the sleeve 22 connects the spring j with the ring of the jack J, whichplaces the cut-ofi relay L and supervisory relay S in series with oneanother with battery in parallel with the line relay L. The cut-ofirelay L thereupon attracts its armatures m, m which disconnect theline-relay L and extinguish the line lamp Z. The supervisory relay Salso attracts its armature and cuts ofi the supervisory lamp 8. Batterycurrent is then supplied to the subscriber through the tip by thesupervisory relay S and through the sleeve by the cut-oft relay L. Theoperator finding that subscriber A is wanted, insert-s the calling plugP in the jack J and rings in the ordinary manner. The insertion of theplug P into the jack J causes battery current to flow through thesupervisory'lamp 8 through the windings of the line relay L to ground.The armatures m m are then attracted. Armature m connects the cut-ofirelay through the contact 0 of the line-relay L and by the wire 7 Thecut-ofi relay L then attracts its armature and cuts off the line relay Land is kept locked by battery current flowing through the supervisorylamp .9 through the contact 0 and the armature m The cutofi relay L iswound so that enough current is passed to allow the lamp 8 to glow.Battery current is then supplied to subscriber A through the tip by thesupervisory relay S and through the sleeve by the cut-oflf relay L Whenthe subscriber A answers he closes the line-circuit 1 and 2 which causesbattery current to flow through the supervisory relay and attracts itsarmature and extinguishes the lamp 8. When the subscribers A, A hang uptheir telephones at the end of the conversation, the armatures of thesupervisory relays S and S fall back and cause their respective lamps s,s to glow. The operator upon seeing these signals withdraws the plugsfrom the line jacks J, J, and the apparatus assumes its normal positionand condition. By way of reversing these conditions, suppose subscriberA calls for subscriber A. In calling, the linecircuit is closed andcurrent flows from main battery B by the back contacts of the cutofirelay L through the winding of line relay L which attracts its armaturesm and m The attraction of the armatures closes circuit 8 and causes theline lamp Z to glow and at the same time completes the circuit of thecut-off relay L through the contact 0". This cut-ofl relay is sluggishin its action and the amount of current derived from the subscribersline with the line relay L in parallel will not attract its armatures.The operator perceiving the line signal inserts the answering plug Pinto the line jack J. This insertion causes an extra amount of currentto flow over the sleeve from the supervisory lamp .9 through the cut-offrelay L which then attracts its armatures m m and cuts oil' theline-relay L and extinguishes the line lam Z. Battery current issupplied to subscrlber as in the first operation over the tip from thesupervisory relay S and over the sleeve from the cut-off relay L Assubscriber A is wanted the operator inserts the calling plug P into thejack J. This insertion causes current to pass through the supervisorylamp 8, through the winding of cut-off relay L, which then attracts itsarmatures and cuts oil the line relay L. This cut-ofi' relay is Wound sothat it passes enough current to make the supervisory lamp 8 glow.Battery current is supplied to subscriber A as in the first operation;through the tip supervisory relay S and through the sleeve by thecut-off relay L. The subscriber A upon answering causes current to fiowthrough the supervisory relay S, which attracts its armature andextinguishes supervisory lamp 8. At the end of the conversation theoperator get-ting the disconnect signals when the subscribers hang uptheir telephones, withdraws the plugs and the apparatus is restored toits normal position.

Referring to Fig. 2, I show a modification of the cord circuit in whicha relay S or S is substituted for the lamp in the cord circuit bridge,the lamp itself being in a separate branch to ground closed whentherelay S or S is energized. Since the supervisory relay 8- or S issimultaneously energized however, the lamp is always open circuited whenthe cord is in use and conversation is proceeding.

Having thus described my invention what I claim and desire to secure byLetters Patent is:

In a telephone exchange system,.line circuits, a line relay and acut-off relay for each line, each line terminating on a pair of contactsin its cut-off relay, one of which is normally connected through acooperating contact with one side of main battery, and the other througha corresponding cooperating contact with the windings of the line relayand thence to the other side of battery, a signal lamp having itscircuit extended from one side of battery through normally closedcont-acts on the cut-off relay and normally open contacts on theassociated line relay to the other side of battery, a jack for each linehaving three contacts, one connected to each side of line direct and thethird to the cut-oii relay and thence to one side of battery, a linkcircuit for interconnecting the lines having terminal plugs eachprovided with tip and sleeve contacts, the latter of sufficient lengthto bridge together the contacts connected to one side of line and to thecut-oii relay respectively, a supervisory relay in the link having itscircuit extended from one side of battery to the tip conductor, a lampcontrolling relay having its circuitextending from battery throughnormally closed contacts in the supervisory relay to the sleeveconductor, and a supervisory signal lamp having its circuit extendedfrom the battery through normally open contacts in the controlling relayto the other side of the battery, whereby when a subscriber calls,current will flow in his line through the line relay only, and when aplug is inserted, current will flow to the line through the cut-offrelay only on one side and through the supervisory relay in the link onthe other, the line relay, the line signal lamp, the controlling relayin the link, and the supervisory lamp in the link being all disconnectedand deprived of current during conversation.

In testimony whereof I have affixed my signature in presence of twowitnesses.

EDWVARD E. CLEMENT.

Witnesses:

THOMAS DUnAN'r, MELVILLE D. CHURCH.

Copies of this patent niay be obtained for five cents each, byaddressing the Commissioner of latents,

Washington, D. 0.

